1. Field of the invention
The present invention relates to a device for the transfer of a threading strip or a material web in a machine for the production and/or processing of the material web, from a pick-up area to a transfer area along a web travel path, and a method for the transferring of a threading strip or a material web.
2. Description of the related art
Devices and methods of the type addressed here are already known (DE 40 37 661 C1). These are utilized in machinery for the production and/or the conversion of a material web and serve to transfer the material web, or a strip which has been slit off the web, also referred to as threading strip, from a pick-up area to a transfer area. During start-up of the machinery, or following a web break, the threading strip or the material web in its entire width, are guided along a web travel path that is established by the guide arrangements and/or the processing units. This process is also known as threading. The known apparatus includes a rope guide arrangement whereby two points converge in a so-called rope nip at the beginning of the rope guide arrangement. The threading strip/material web is led into rope nip which is located in a pick-up area and is held between the ropes. The threading strip/material web is carried together with the ropes along the web travel path into a transfer area in which the threading strip/material web is transferred into a downstream unit in the machine. The transfer takes place at reduced or full machine speed, which may be 2,000 m/min. or higher. In fact, the ropes which are used for the transfer often run at even higher speeds than the machine speed. It has proven disadvantageous that the threading strip/material web in many instances cannot be held securely by the ropes, thus getting lost during the transfer. The result is that the transfer process must often be repeated several times, until a successful transfer of the threading strip/material web from the pick-up area to the transfer area is concluded. However, web breaks occur frequently after the transfer, due to the fact that the threading strip/material web oscillates while being put under tension in a longitudinal direction, thereby enabling them to run back into the ropes where they are destroyed. These multiple attempts to achieve a successful transfer increase machine down times and thereby decrease productivity.
The present invention provides an apparatus and a method which ensures a reliable transfer of a threading strip or a material web, even at high machine speeds.
The at least one pick-up apparatus of the present invention, for the purpose of transferring the threading strip/material web from the pick-up area to the transfer area, is movable essentially along the web travel path at a speed that is lower and preferably considerably lower than the operating speed with which the threading strip/material web travels through the machine during the transfer process. Consequently, a high degree of operational reliability is assured. In the context of the present invention the term xe2x80x9cweb travel pathxe2x80x9d relates to the path which is projected by the production and/or conversion process of the material web, or by the guide assemblies and or processing units. The threading strip/material web, for example, is carried over rolls, through roll presses, over device surfaces, over/through processing devices, over/through measuring devices and/or on belts whose location inside the machine determine or establish the web travel path. The pick-up apparatus is moved along the web travel path at a lower speed than the threading strip/material web whose speed during the transfer process is consistent with the machine speed. With the assistance of the pick-up apparatus, the threading strip/material web is guided out of the web travel path, sideways for example, at the location at which the pick-up apparatus is positioned in the machine. Since the relocation speed of the pick-up apparatus is lower, preferably considerably lower than the running speed of the threading strip/material web, it is impossible for the material web to wrap onto the pick-up apparatus. Threading of the strip/web is therefore also possible at very high machine speeds since the transfer speed, that is the relocation speed, of the pick-up apparatus is variable independently from the operating. speed of the machine.
A preferred embodiment of the transfer device is an apparatus in which the pick-up assembly is movable in the direction of the web travel and in an opposite direction thereto. This permits open travel of the pick-up apparatus. Consequently, the pick-up apparatus does not have to be directed in a circle in order to relocate it from the transfer area to the pick-up area. Instead, it can be brought back to the pick-up area in a direction opposite to the direction of web travel. The relocation speed and direction of the pick-up apparatus would preferably be variable between the two transfer processes.
A particularly favored embodiment of the invention provides that the relocation speed during a transfer process is variable and preferably adjustable. Viewed in a direction of web travel, the threading strip/material web can therefore travel at different speeds in different sections. This provides for a relatively fast and reliable transfer since in the area of a processing unit or guide arrangement over/through which the threading strip/material web is carried or threaded, the already relatively low relocation speed may be further reduced.
A preferred embodiment of the transfer device provides a pick-up apparatus that is movable or guided either in the vicinity of the web travel path or outside the web travel path. The travel path of the pick-up apparatus may, for example, be adjusted to the arrangement of the threading strip that has been slit from the material web. The threading strip is slit from the material web either from a web edge or from a material web segment between the web edges. The pick-up apparatus may also be guided in the center of the web travel path. If the material web is transferred in its entire width from the pick-up area into the transfer area, then the pick-up apparatus may also be located, in this instance, in or outside the area of the web travel path. If the pick-up apparatus is located outside the web travel path, then it is designed such that its range of influence extends into the web travel path, at least into the area in which the threading strip/material web is to be guided.
A guide including at least one guide element is assigned to the pick-up apparatus. An advantageous embodiment of the invention provides that the at least one guide element is in the form of rope, belt, chain or similar device. Such a guide elements may be stationary, meaning they may be mounted rigidly, so that the pick-up apparatus can travel (for example, on the guide elements) along the path that is projected by the guide elements, while the guide elements are stationary. A different embodiment provides that the guide element(s) is (are) driven by a drive, so that the pick-up apparatus that is mounted on the guide element can travel along the path that is projected by the guide element(s). It is also feasible that the pick-up apparatus may move relative to the movable guide element.
In accordance with another design variation, the at least one guide element is provided in the form of a roll, preferably a profile roll. The pick-up apparatus can, therefore, be moved with the assistance of rolls which are located along the web travel path and whereby at least some of these rolls are driven.
A preferred embodiment of the transfer device provides that the travel path of the guide arrangement is longer than the web travel path. The travel path, therefore, does not only extend from the pick-up area into the transfer area, or in opposite direction, but also further so that the pick-up apparatus may be guided out of the area of the web travel path. This arrangement allows the pick-up apparatus to be moved, during a machine run for the production and/or processing of the material web, into a position which is not directly adjacent to the web travel path along which the material web travels during the production process. This movement ensures that the pick-up apparatus does not influence or disturb the production and/or the converting process.
In an advantageous embodiment of the transfer device the transfer element can be tied into an endless loop. Specifically, the guide element extends from the pick-up area essentially along the web travel path to the transfer area and from the transfer area back to the pick-up area. In the context of the present invention the term xe2x80x9cextendsxe2x80x9d refers to a guide arrangement, as well as to a configuration of the guide element. The guide element is movably located or is stationary within the machine. This set-up permits for example that, following the transfer process, the pick-up apparatus will continue to be moved or guided along in the same direction, for example until reaching the pick-up area. The pick-up apparatus can therefore always be moved in the same direction.
Another preferred design arrangement of the transfer device includes a pick-up apparatus having a pick-up head with at least one pick-up orifice. During pick-up of the threading strip/material web, the strip/web are guided into this opening by a suitable device. Preferably, a further processing unit would be located downstream from the pick-up head. In the context of the current invention, the term xe2x80x9cfurther processing unitxe2x80x9d relates to equipment in which the section of threading strip/material web which was directed out of the web travel path during the transfer process is reduced in size, incinerated, dissolved, and/or transported into containers, baskets, screens, nets by utilizing, for example, fire, at least one of a gaseous and a liquid medium, choppers, water torches, or water screens. A further processing unit may therefore take the form of a size reduction, incineration, dissolving, collection, waste removal and/or recycling unit.
In an advantageous example of an embodiment, the section of threading strip/material web that is taken into the pick-up orifice of the pick-up head is, for the purpose of further processing, directed immediately out of the machine, for example sideways. That section is then captured or thrown directly onto the floor on which the machine is standing. The cost expenditures for a transfer device of this type are relatively low.
A preferred embodiment of the transfer device would be one in which the pick-up orifice is connected with a tube through which the threading strip/material web is removed from the web travel path, during a transfer process. With the assistance of the preferably flexible tube, the section of the threading strip/material web which has been directed out of the web travel path may, for example, be directed out of the machine sideways and into a device for further processing.
An advantageous embodiment provides that a gas or fluid flow can be admitted, at least in sections, to the preferably flexible tube, channel or similar device, with which the pick-up orifice is connected. The flow serves to carry that part of the threading strip/material web which has been directed out of the web travel path and which travels at a higher velocity than the pick-up unit. During this operation the threading strip/material web may, for example, be already (chemically) dissolved. By controlling the flow, the longitudinal tension of that part of the threading strip/material web which has already been transported from the pick-up area, along the web travel path to the pick-up apparatus, for example, directly to the pick-up orifice of the pick-up head, can be adjusted.
A particularly preferred example of the transfer device has at least one vacuum source with which the inlet opening on the pick-up head can be supplied with a vacuum, preferably being variable. The vacuum source may, for example, be allocated to the pick-up apparatus or may be integrated directly into the pick-up head so that a compact structure of the pick-up apparatus remains feasible. In an advantageous design variation a blower is utilized as the vacuum source. Such a blower can at the same time be used to reduce the threading strip/material web in size, for example, with an appropriately designed blower blade.
A further embodiment example of the transfer device provides that the vacuum source is provided by an injector. This injector may be located directly at the pick-up apparatus or may be integrated thereinto. Additionally, the injector may be located stationary inside the machine and connected through a tube or a channel system with the pick-up orifice of the pick-up head. The injector may be driven by use of a liquid, for example, water; and/or a gas flow, for example, air or water vapor.
Another preferred example of an embodiment provides a transport assembly for capturing the threading strip/material web which is located in the area of the pick-up head. The transport assembly may, for example, be in the form of a pull press, whose rolls are rubberized, are brushes, or are designed as chopping rolls. It is also feasible to utilize a shredding ventilator or standard shredder as the transport assembly, which would reduce the threading strip/material web in size. Other examples of the transport assembly are at least one vacuum belt, also known as a Fibron belt, onto which the threading strip/material web is held by a vacuum; at least one so-called Coanda plate; at least one suction drum around certain sections of the circumference of which the threading strip/material web is held by a vacuum; and/or a twisting device. The configuration of the transport assembly is practically whatever is desired. It is important however, that the threading strip/material web is captured, meaning, that it can be held and/or transported.
In another design variation a transfer assist device is provided between the two pick up devices, which takes the threading strip/material web from the first pick-up unit and transfers it/them to the second pick-up unit. The transfer assist device, which may include a Fibron belt, bridges the area between the pick-up units which are located at a distance from each other.
The at least two pick-up units provided in a preferred design variation may be of the same or of a different design. The pick-up units may, for example, have different drives and/or different pick-up heads. It is also feasible that the pick-up units share a common guide arrangement or have separate guides which may or may not be of the same design.
A transfer device design is preferred which includes at least one sensor with which the pressure in the tube, channel or similar device connected to the pick-up head can be determined. In the event of a pressure change in the tube, for example, due to a blockage, the transfer process can be interrupted or stopped and/or the vacuum in the tube increased in order to remove the blockage through suction. By monitoring the pressure, the operational reliability of the transfer device is increased.
The transfer device offers a high degree of operational reliability due to the fact that the threading strip/material web is transported from the pick-up area into the transfer area along the web travel path at a speed which is lower, preferably considerably lower, than the speed with which the threading strip/material web is carried through the machine during the transfer process. The running speed of the threading strip/material web is consistent with the machine speed. To enable transfer of the threading strip/material web at least sectionally at a lower speed than the running speed of the web along the web travel path and to be able at the same time to maintain the longitudinal tension of the threading strip/material web at a desired value, that section of the threading strip/material web which is not yet transferred would preferably be directed out of the web travel path. The method is characterized by a high operational reliability.